1. Field of the Invention
The present invention generally relates to a compact electronic apparatus having a function for displaying a given formula in a graphic representing mode. More specifically, the present invention is directed to a function for tracing a point on the displayed graphic representation.
2. Description of the Related Art
Conventionally, compact electronic calculators equipped with a graphic display function have been commercially available, by which inputted function formulae are displayed in a graphic representation on a dot matrix type liquid crystal panel. Such a sort of compact electronic calculators are equipped with a trace function that a pointer is displayed in a flicker mode on the displayed graphic representation and the coordinate data representative of the pointer is displayed. In this case, for instance, the pointer may be moved by 1 dot along the X direction every time the trace pointer moving key is operated.
Also in the conventional calculators, when a plurality of function formulae are inputted, these function formulae are successively displayed one by one in the graphic representation on the display unit every time the excution key ("EXE" key) mounted on the key input unit is depressed. In this case, the graphic representations which have been displayed up to the previous key operation are not erased, but are displayed in conjunction with the present graphic representation. Such a representation form is so-called "overlaying graphic representation".
Function formulae to be graphically represented may be displayed not only by way of a form of y=f(x), but also by way of an inequality such as y&gt;f(x).
However, in case that a trace operation is performed after displaying the graphic representation, although a plurality of graphs are displayed in the overlaying graphic representation mode on the display unit, the tracing operation cannot be excuted with respect to only the last one graphic representation.
Furthermore, when an inequality is traced, it is required to clarify whether coordinate data on a pointer flickered on a graphic representation is contained (namely.gtoreq., .ltoreq.), or not (namely &gt;, &lt;).
In case that coordinate data on the graphic representations are sequentially obtained by operating the trace pointer moving key, since the display pixel is moved in unit of only 1 dot, it is very inconvenient for operators that a lenghty time is required so as to move the pointer to a desirable moving place.
As previously explained, although the conventional calculators with the graphic function are equipped with the above-described trace function, any operators can feel the actual use of such a function inconvenient.